If you're contemplating your own humility, that's not a very humble act. Likewise, aikidoka talking amongst themselves about their humility is kind of ridiculous.
Personally, I must say that the couple of times I have done any sparring, it was a pretty humbling experience... which is not to say that sparring and such lead to humility.
The only way to be humble is to realize that however good you are, there are always going to be people out there who are better than you are.
If that isn't the case for some reason, you're probably enlightened, so it becomes a bit of a moot point *grin*